Adjustable passive chokes

ABSTRACT

Adjustable passive choke devices, systems, and methods for controlling fluid flow rate, pressure, or both, are provided. The adjustable passive choke devices may include a fluid conduit having a first end, a second end, and an intervening portion positioned in between the first and second ends, the intervening portion having a flow resistance element for reducing a flow rate of a fluid when the fluid is passed through the fluid conduit from the first end to the second end. The devices may also include a selectable bypass line, which is connected upstream and downstream of the flow resistance element and provides a fluid flow bypass path bypassing at least a portion of the flow resistance element when activated.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Canadian PatentApplication No. 2,958,979, filed Feb. 24, 2017, the entire contents ofwhich are hereby incorporated by reference in its entirety.

FIELD OF INVENTION

The present disclosure relates generally to devices and methods forcontrolling flow rate and/or pressure. More specifically, the presentdisclosure relates to adjustable passive choke devices for controllingflow rate and/or pressure within a system.

BACKGROUND

Passive choke devices are commonly used in many industrial processes andsystems to control or regulate flow rate. Passive chokes typicallyinclude one or more elements or structures which resist, or choke, theflow of fluid when passed therethrough. As a result, the inclusion of apassive choke device within a pipeline or other fluid transport systemallows for the fluid flow rate within the system to be reduced, therebyproviding a measure of control over fluid flow rate. Passive chokedevices are typically designed to avoid excessive energy requirementsand/or constant upkeep, and instead provide for flow reduction usingpassive design elements such as flow restricting sections, loops orcoils, bends, narrowed sections, or other flow path modifying designswhich reduce fluid flow rate via frictional line loss and/orbackpressure.

Passive choke devices have proven particularly useful in systemsinvolving a common line or feed line, which provides fluid to two ormore fluid distribution lines having differing backpressure or othercharacteristics affecting flow rate. By way of example, chemicalenhanced oil recovery (EOR) operations typically involve two or morepolymer injection wells (i.e. fluid distribution lines) which are fedpolymer by a common line. As each individual injection well may beinjecting polymer into deposits having different depths, access paths,and/or backpressures, situations are commonly encountered where fluidflows more readily through one injection well as compared with another.In such conditions, polymer from the common line will become unevenlydistributed, with an increased proportion being diverted to theinjection well(s) having the least resistance to fluid flow.

Such unequal fluid distribution profiles are frequently corrected inoilfield operations using a form of passive choke device known as a coilchoke. Coil chokes typically comprise a fluid conduit which is coiled orlooped, such that fluid flowing through the fluid conduit navigates oneor a plurality of coils, which have the effect of increasing fluid flowpath length, and reducing fluid flow rate via frictional line loss. Acoil choke will commonly include a plurality of in-line coils, whichhave an additive effect on reducing flow rate through the fluid conduit.An oilfield operator will commonly install a coil choke on injectionwell(s) of the system having the least resistance to fluid flow in aneffort to equalize fluid flow rates between the different injectionwells, thereby allowing for substantially equal polymer distributionassuming flow characteristics remain constant between the injectionwells.

In the oil and gas industry, operators will typically determine whichinjection wells are in need of decreased fluid flow rate so as toequalize the system, and then install coil chokes on these injectionwells to reduce fluid flow rate therethrough. As the amount of fluidflow resistance needed will vary between injection wells, operatorstypically manually cut, splice, or remove sections (i.e. remove coils,or portions thereof) from the coil choke until the device provides theproper amount of fluid flow resistance to meet the demands of theparticular injection well being corrected. As the flow characteristicsof an injection well can change over time, manual adjustments toinstalled coil chokes may be needed in an ongoing fashion, increasingcosts and operational downtime.

An alternative, additional, and/or improved passive choke device forcontrolling flow rate is desirable.

SUMMARY

Provided herein are adjustable passive choke devices comprising aselectable bypass line operable to provide a fluid flow bypass pathbypassing all, or a portion, of a flow resistance element whenactivated. Certain embodiments of such devices may allow for adjustmentof the fluid flow resistance properties of the passive choke without theneed for time-consuming manual cutting/splicing operations. Rather,control over fluid flow rate and/or pressure may be realized byactivating, or deactivating, the selectable bypass line as needed tosuit the flow rate demands of the particular system. Operation ofdevices, as provided herein, may even be automated, further reducingoperational demands on an ongoing basis.

In an embodiment, there is provided herein an adjustable passive chokedevice for controlling fluid flow rate and/or pressure, said devicecomprising: a fluid conduit having a first end, a second end, and anintervening portion therebetween, the intervening portion comprising aflow resistance element configured for reducing a flow rate of a fluidwhen the fluid is passed through the fluid conduit from the first end tothe second end; and a selectable bypass line connected upstream anddownstream of at least a portion of the flow resistance element, theselectable bypass line being configured to provide a fluid flow bypasspath bypassing at least a portion of the flow resistance element whenactivated; whereby activation of the selectable bypass line configuresthe adjustable passive choke device for increased flow rate by at leastpartially opening the fluid flow bypass path, and deactivation of theselectable bypass line configures the adjustable passive choke devicefor decreased flow rate by at least partially closing the fluid flowbypass path.

In one implementation, the selectable bypass line comprises two or moreupstream connections, downstream connections, or both, and is configuredto provide a plurality of selectable fluid flow bypass paths, with eachpath bypassing a different proportion of the flow resistance element.

In one implementation, the flow resistance element may comprise one ormore loops or coils for reducing fluid flow rate by frictional lineloss.

In one implementation, the device further comprises one or more valvesfor controlling fluid flow through the selectable bypass line.

In one implementation, the device further comprises a flow meterdownstream of the flow resistance element for determining fluid flowrate.

In one implementation, the device further comprises one or more pressuregauges or pressure sensors for determining pressure downstream of thedevice.

In one implementation, the device further comprises one or more pressuregauges or pressure sensors for determining a pressure drop (Δpressure/length) across at least one portion of the flow resistanceelement.

In one implementation, the device further comprises a programmable logiccontroller (PLC) for controlling fluid flow through the selectablebypass line.

In one implementation, the activation and the deactivation of theselectable bypass line and selection of at least one fluid flow bypasspath from the plurality of selectable fluid flow bypass paths, isautomated, such that the fluid flow rate or downstream pressure ismaintained at a predetermined value, above a predetermined lower limit,below a predetermined upper limit, or within a predetermined range.

In one implementation, the activation and the deactivation of theselectable bypass line and the selection of the at least one fluid flowbypass path, is determined at least in part by at least one of ameasured flow rate parameter, a measured pressure drop parameter, or ameasured downstream pressure parameter.

In one implementation, the device further comprises two or more flowresistance elements.

In one implementation, the two or more flow resistance elements areconfigured to provide the same or different resistance to fluid flowtherethrough.

In one implementation, the selectable bypass line is configured toprovide one or more fluid flow bypass paths bypassing at least a portionof the two or more flow resistance elements.

In one implementation, the device further comprises two or moreindividually selectable bypass lines, with each configured to providedifferent fluid flow bypass paths when activated.

In one implementation, the adjustable passive choke device may beconfigured for controlling flow rate and/or downstream pressure throughan injection well in an oil recovery operation or through an industrialwater injection operation.

In one implementation, the flow resistance element comprises a 2×multiplier configuration for providing incremental doubling of length orflow resistance between portions of the flow resistance element.

In another embodiment, a method for controlling fluid flow rate orpressure through at least one fluid distribution line, comprisesproviding an adjustable passive choke device having a fluid flow bypasspath; passing a fluid through the adjustable passive choke device;controlling the fluid flow rate by performing at least one of:increasing the fluid flow rate by at least partially opening the fluidflow bypass path; and decreasing the fluid flow rate by at leastpartially closing the fluid flow bypass path, such that the at least onefluid distribution line is configured as at least one injection well inan oil recovery operation or in a water injection operation.

In yet another embodiment, there is provided herein a fluid transportsystem comprising: at least one fluid distribution line; a common linefor supplying a fluid to the at least one fluid distribution line; apump for supplying the fluid to the common line, and at least oneadjustable passive choke device described herein positioned before orwithin the at least one fluid distribution lines for controlling fluidflow rate therethrough or pressure downstream thereof.

In one implementation, the fluid transport system further comprises aprogrammable logic controller (PLC) for controlling the at least oneadjustable passive choke device.

In one implementation, the fluid transport system further comprises atleast two fluid distribution lines, wherein the at least one adjustablepassive choke device is configured to control fluid flow rate such thatthe fluid flow rate through the at least two fluid distribution lines issubstantially equal, or whereby the ratio of fluid flow rate between theat least two fluid distribution lines is: maintained at a predeterminedratio, above a predetermined lower ratio limit, below a predeterminedupper ratio limit, or within a predetermined ratio range.

In one implementation, the at least one adjustable passive choke deviceis configured adapt to changes in fluid flow resistance in the at leasttwo fluid distribution lines, whereby the fluid flow rate or pressurethrough the at least two fluid distribution lines remains substantiallyconstant, or within a predetermined range.

In one implementation, the fluid distribution lines are injection wellsin an oil recovery operation or in water injection operations.

In yet another embodiment, there is provided herein a method forcontrolling a flow rate or pressure of a fluid through a fluiddistribution line, said method comprising: reducing the fluid flow rateby passing the fluid through a flow resistance element; and increasingthe fluid flow rate by passing the fluid through a fluid flow bypasspath which bypasses all, or a portion, of the flow resistance element;as needed so as to maintain the flow rate, the pressure, or both, of thefluid through the fluid distribution line at predetermined value(s),above predetermined lower limit(s), below predetermined upper limit(s),or within predetermined range(s).

In one implementation, the method is performed by operating at least oneof the adjustable passive choke device described herein.

In one implementation, the method is an automated method performed by aprogrammable logic controller (PLC).

In one implementation, the fluid distribution line is an injection wellof an oil recovery operation or of a water injection operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of one embodiment illustrative of an adjustablepassive choke device for controlling fluid flow rate and/or pressure asdescribed herein. The illustrated embodiment is a coil choke-typepassive choke, which is installed at an injection well head in anoilfield operation. The illustrated device is for regulating fluid flowrate from a common (supply) line to the injection well under theoptionally automated control of a programmable logic controller (PLC)configured to maintain flow rate within a pre-determined flow rate rangeas measured at a flow meter located downstream of the coil portion ofthe coil choke by operating valves controlling fluid flow through fluidflow bypass paths provided by selectable bypass lines of the adjustablepassive choke device.

DETAILED DESCRIPTION

Described herein are adjustable passive choke devices, systems, andmethods for controlling fluid flow rate and/or pressure. It will beappreciated that embodiments and examples are provided for illustrativepurposes intended for those skilled in the art, and are not meant to belimiting in any way.

In one embodiment, there is provided herein an adjustable passive chokedevice for controlling fluid flow rate, said device comprising:

-   -   a fluid conduit having a first end, a second end, and an        intervening portion therebetween, the intervening portion        comprising a flow resistance element for reducing a flow rate of        a fluid when the fluid is passed through the fluid conduit from        the first end to the second end; and    -   a selectable bypass line connected upstream and downstream of        the flow resistance element, or a portion thereof, operable to        provide a fluid flow bypass path bypassing all, or a portion, of        the flow resistance element when activated;        whereby activation of the selectable bypass line configures the        adjustable passive choke device for increased flow rate by at        least partially opening the fluid flow bypass path, and        deactivation of the selectable bypass line configures the        adjustable passive choke device for decreased flow rate by at        least partially closing the fluid flow bypass path.

As will be understood, the fluid conduit may be any suitable fluidchannel, line, conduit, or other structure capable of transporting afluid such as a liquid, gas, or combination thereof. Suitable fluidconduits may include, for example, a pipe, hose, tube, or other suchstructure. Fluid conduits will typically include an outer wall definingan internal passage through which a fluid may pass.

As will also be understood, a flow resistance element may be anysuitable structure or component for reducing a flow rate of a fluidpassing therethrough. Suitable flow resistance elements may include, forexample, flow restricting sections, loops or coils, bends, narrowedsections, turbulence-inducing structures, or other flow path modifyingdesigns which reduce fluid flow rate via frictional line loss and/orincreased backpressure, for example. In coil choke-type embodiments, asuitable flow resistance element may comprise, for example, a pluralityof in-line coils or loops, each of which provides an additive-type flowresistance via frictional line loss such that fluid flow rate isincreasingly reduced with each sequential coil or loop traversed. Theskilled person having regard to the teachings of the instant applicationwill be aware of several flow resistance element options, and will beable to select a suitable flow resistance element to suit a particularapplication.

In certain embodiments, it will be understood that suitable flowresistance elements may include those comprising, for example, aplurality of flow restricting sections, loops or coils, bends, narrowedsections, turbulence-inducing structures, or other flow path modifyingdesigns which reduce fluid flow rate via frictional line loss, which maybe arranged in series, each providing an additive-type flow resistancevia frictional line loss. The flow resistance contribution from eachindividual member of the plurality may be substantially the same orsimilar, or may differ between members. By way of example, in coilchoke-type embodiments, suitable flow resistance elements may includethose comprising a plurality of coils or loops arranged in series, eachproviding an additive-type flow resistance via frictional line loss. Theplurality of coils or loops may each be the same or similar in length,or may have differing lengths.

In certain embodiments, flow resistance elements may include thosecomprising, for example, a plurality of flow restricting sections, loopsor coils, bends, narrowed sections, turbulence-inducing structures, orother flow path modifying designs which reduce fluid flow rate, eachproviding an additive-type flow resistance, whereby the individualmembers of the plurality are selected so as to co-operate with oneanother to provide a flow resistance which is highly adjustable throughselection of active bypass line(s). In certain embodiments, a 2×multiplier, for example, may be used for selecting such a co-operativeplurality of members.

By way of a further example, in coil choke-type embodiments, suitableflow resistance elements may include those comprising a plurality ofcoils or loops arranged in series, each providing an additive-type flowresistance via frictional line loss. In certain examples, the pluralityof coils or loops may be designed using a 2× multiplier. In suchexamples, the plurality of coils or loops may comprise a set of coils orloops which incrementally double in length between members of the set(i.e. the coil or loop members of the set may have lengths of n, 2(n),4(n), 8(n), 16(n), 32(n), etc. . . . , wherein n is the length of theshortest member in the set). By way of illustrative example, the flowresistance element may be a coil choke-type flow resistance elementcomprising a set of coils having lengths of 1 m, 2 m, 4 m, 8 m, and 16m, respectively. If an individually selectable bypass line is connectedupstream and downstream of each coil of the set so as to provide a fluidflow bypass path bypassing each individual coil of the set whenactivated, then such an adjustable passive choke device may beconfigured to provide 1 m, 2 m, 3 m, 4 m, 5 m, 6 m, 7 m, 8 m, 9 m, 10 m,11 m, 12 m, 13 m, 14 m, 15 m, 16 m, 17 m, 18 m, 19 m, 20 m, 21 m, 22 m,23 m, 24 m, 25 m, 26 m, 27 m, 28 m, 29 m, 30 m, or 31 m of flowresistance coil length as desired. Such devices thus may provide highlyadjustable flow resistance, allowing fine adjustment of flow rate bycontrolling which individually selectable bypass lines areactive/inactive.

In the example above, the plurality of coils or loops implement a 2×multiplier by incrementally doubling in length. It will be understood,however, that other configurations implementing a 2× multiplier may alsobe possible. For example, the plurality of coils or loops may comprise aplurality of coil or loop subsets, where the number of coils or loops ineach subset incrementally doubles in number between subsets (i.e., theplurality of coils or loops may comprise a subset having n coil(s) orloop(s), a subset having 2(n) coils or loops, a subset having 4(n) coilsor loops, a subset having 8(n) coils or loops, a subset having 16(n)coils or loops, a subset having 32(n) coils or loops, etc. . . . ,wherein n is the number of coil(s) or loop(s) in the smallest subset).By way of a further illustrative example, the flow resistance elementmay be a coil choke-type flow resistance element comprising a pluralityof coil subsets having 1, 2, 4, 8, and 16 coils, respectively. If anindividually selectable bypass line is connected upstream and downstreamof each subset so as to provide a fluid flow bypass path bypassing eachindividual subset of the plurality when activated, then such anadjustable passive choke device may be configured to provide 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, 30, or 31 coils providing flow resistance, asdesired. Such devices thus may provide highly adjustable flowresistance, allowing fine adjustment of flow rate by controlling whichindividually selectable bypass lines are active/inactive. An example ofan adjustable passive choke device comprising a plurality of coils whichare the same or similar to one another, arranged as subsets implementinga 2× multiplier, is described in further detail in Example 1 below.

As will be understood, a 2× multiplier as described herein may beimplemented in a number of ways. Doubling of length and doubling innumber are described above. It is also contemplated that a 2× multipliermay be implemented using combinations of length and number manipulation,or using any other suitable design or combination of designs affectingflow resistance as will be known to the person of skill in the arthaving regard to the teachings provided herein. 2× multiplierimplementation may include, for example, any suitable design in whichthe flow resistance element may be configured to provide flow resistancewhich is highly adjustable via controlling the activation/deactivationstate(s) of individually selectable bypass line(s) providing fluid flowbypass path(s) bypassing portions of the flow resistance element, theportions each having an additive fluid flow resistance contributionwhich incrementally doubles between portions.

Selectable bypass lines may include any suitable bypass line which isoperable to provide a fluid flow bypass path for fluid which bypassesall, or a portion, of the flow resistance element when activated. Bybypassing all, or a portion, of the flow resistance element, fluidpassing through the fluid flow bypass path provided by the selectablebypass line experiences decreased flow resistance, and thereforeactivation of the selectable bypass line configures the adjustablepassive choke device for increased flow rate. In contrast, deactivationof the selectable bypass line at least partially closes the fluid flowbypass path, causing fluid to pass through the flow resistance elementand experience increased flow resistance, configuring the adjustablepassive choke device for increased flow rate.

It will be recognized that selectable bypass lines may comprise anysuitable fluid channel, line, conduit, or other structure capable offorming at least one continuous fluid flow bypass path when activated.Suitable selectable bypass lines may include those comprising a pipe,hose, tube, or other such structure, for example. Selectable bypasslines will typically include an outer wall defining an internal passagethrough which a fluid may pass.

As will be understood, in certain embodiments, the selectable bypassline may be connected or located upstream and downstream of the flowresistance element, or a portion thereof. In certain embodiments, theselectable bypass line may comprise one, two, or more upstreamconnections; one, two, or more downstream connections; or both; so as toprovide a plurality of selectable fluid flow bypass paths, eachbypassing a different proportion or section of the flow resistanceelement.

By way of illustrative example, an adjustable passive choke device asdescribed herein may include a flow resistance element comprising aplurality of coils. In such an embodiment, the selectable bypass line ofthe adjustable passive choke device may comprise a plurality of upstreamconnections positioned before each of the coils, and a downstreamconnection positioned after the last coil. Such configuration wouldallow the selectable bypass line to be operable to provide a pluralityof fluid flow bypass options, each bypassing a different number of coilsof the flow resistance element. By choosing which upstream connection isoperable when the selectable bypass line is activated, the flowresistance provided by the adjustable passive choke device can beadjusted as desired by allowing fluid to bypass all, or a portion, ofthe coils of the flow resistance element.

As will also be understood by the person of skill in the art havingregard to the teachings herein, activation and deactivation of theselectable bypass line, and accompanying flow of fluid through the flowresistance element, the fluid flow bypass path provided by theselectable bypass line, or both, may be controlled using any suitablefluid flow control mechanism known to the person of skill in the art. Byway of example, fluid flow through the adjustable passive choke devicemay be directed by valves, switches, apertures, or other suitablefluid-directing mechanisms. In certain embodiments, fluid flow may becontrolled by one or more valves (for example, solenoid valves)controlling fluid flow through the flow resistance element, the fluidflow bypass path provided by the selectable bypass line, or both.Exemplary valves may be those which direct fluid to either the flowrestriction element or the fluid flow bypass path, or may be those whichare capable of directing a portion of the fluid to the flow restrictionelement, and another portion to the fluid flow bypass path. By varyingthe proportion of fluid flowing to the flow restriction element versusthe fluid flow bypass path, for example, the flow resistance provided bythe adjustable passive choke device may be varied to meet changing flowresistance demands in a system.

In certain further embodiments, adjustable passive choke devices asdescribed herein may include, or may interface with, one or more flowmeters and/or pressure gauges/sensors, optionally located downstream ofthe flow resistance element, for determining fluid flow rate and/ordownstream pressure. The skilled person will be aware of a variety ofsuitable flow meters, pressure gauges, and pressure sensors, and will beable to select suitable meter(s), gauge(s), or sensor(s) to suit aparticular application. Such flow meters may provide a flow rateread-out allowing for assessment of flow through the system and, ifdesired, adjustment of the adjustable passive choke device to increaseor decrease flow resistance in accordance with the flow rate demands ofthe particular system. Such pressure gauges or sensors may provide adownstream pressure read-out allowing for assessment of pressure in thesystem and, if desired, adjustment of the adjustable passive chokedevice to increase or decrease flow resistance in accordance with thepressure demands of the particular system.

In certain embodiments where a coil choke-type design is used, thepressure drop across the coils (i.e. (Δ pressure)/(length)) may bedetermined and used in designing and/or controlling the flow resistanceelement. Typically, pressure and/or Δ pressure will be a site specificmetric, and the design may be adapted for the specific site metrics aswill be appreciated by the person of skill in the art in view of theteachings herein. For example, viscosity, flow rate, and/or pressuredifferential (i.e. pressure differential desired between different fluiddistribution lines) factors of a given system may be considered whenselecting coil length and diameter, such that pressure drop across thecoils (i.e. (Δ pressure)/(length)) is appropriate for the particularapplication. As well, knowing the pressure drop across the coils (i.e.(Δ pressure)/(length)), and/or monitoring the pressure drop across thecoils (i.e. (Δ pressure)/(length)) on an ongoing basis, may be used toinform control over activation/deactivation of the selectable bypassline(s) of adjustable passive choke devices so as to assist inmaintaining a desired flow rate in the system. One or more pressuregauges and/or other gauges or sensors may be used for determiningpressure drop across the coils (i.e. (Δ pressure)/(length)), forexample.

As will be recognized, in certain applications and/or systems, pressurelimits on downstream flow (for example, license pressure of a well orwells) may exist or may be desirable. In such applications and/orsystems, it downstream pressure may be monitored by one or more pressuresensors, and the adjustable passive choke devices as described hereinmay be operated to regulate or control pressure, or flow rate andpressure, as desired for the particular application. By way of example,in certain embodiments, an adjustable passive choke device as describedherein may be used to reduce flow rate to one or more destinations,thereby reducing the pressure at the one or more destinations so as tomaintain said pressure within a particular range, or below a particularupper limit, for example. Thus, it will be understood that adjustablepassive choke devices as described herein may be for controlling fluidflow rate, for controlling downstream pressure, or both fluid flow rateand downstream pressure.

As will be understood, in certain embodiments, adjustable passive chokedevices as described herein may be amendable to automation, therebyallowing for ongoing control of fluid flow rate and/or pressure. In anembodiment, fluid flow through the selectable bypass line of theadjustable passive choke device may be controlled by a programmablelogic controller (PLC), or another computer-based controller. Such PLCsor other computer-based controllers may include a memory on whichexecutable instructions for operation of the adjustable passive chokedevice may be stored. The executable instructions may be executed by aprocessor or microcontroller of the PLC in order to configure the PLC orother computer-based controllers to provide control of the adjustablepassive choke device(s). The PLC may be implemented in various waysincluding as, for example, an application-specific integrated circuit(ASIC) or a field programmable gate array (FPGA), or otherimplementation combining a processing unit and memory. The PLC mayreceive input from one or more flow sensors monitoring a flow rateand/or other characteristics, and may control the fluid flow through theselectable bypass line or lines of the adjustable passive chokedevice(s) according to control logic to, for example, maintain ameasured flow rate, a measured downstream pressure, or both within aparticular target range or target ranges. The PLC may provide one ormore output signals for activating or deactiving valves that control thefluid flow within the bypass lines. In addition to the executableinstructions, the memory may further store certain operational targetsor other operational parameters such as, but not limited to, apredetermined target flow rate value, a predetermined target lower flowrate limit, a predetermined target upper flow rate limit, apredetermined target acceptable flow rate range, a predetermined targetdownstream pressure value, a predetermined target lower downstreampressure limit, a predetermined target upper downstream pressure limit,or a predetermined target acceptable downstream pressure range. Incertain embodiments, one or more device characteristics such as flowresistance element properties (such as, for example, the flow resistancecontribution provided by each portion or subset of the flow resistanceelement, the pressure drop across each portion or subset of the flowresistance element, the length of each portion or subset of the flowresistance element, etc. . . .) may be stored on the memory portion andused in determining which selectable bypass line(s) toactivate/deactivate to achieve or maintain a desired flow rate and/orpressure.

During operation, such automated adjustable passive choke devices maymonitor flow rate and/or pressure on an ongoing basis, and adjust flowresistance provided by the adjustable passive choke device (viaactivation or deactivation of the selectable bypass line and/orselection of the fluid flow bypass path where more than one is providedby the selectable bypass line) as needed such that flow rate and/orpressure is maintained at a predetermined value, above a predeterminedlower limit, below a predetermined upper limit, or within apredetermined range, for example. Such devices may, for example, includea PLC or other computer-based controller which electronically controlsoperation of valves within the device which function to activate ordeactivate the selectable bypass line and/or select the fluid flowbypass path where more than one is provided by the selectable bypassline.

As will be understood, adjustable passive choke devices as describedherein may include any of a variety of different configurations, andmany modifications may be possible. By way of example, in certainembodiments devices may comprise two or more flow resistance elements.Such flow resistance elements may each provide the same, or different,resistance to fluid flow therethrough. Such devices may include aselectable bypass line which is operable to provide one or more fluidflow bypass paths bypassing all, or a portion, of the two or more flowresistance elements, or may include two or more individually selectablebypass lines which are each operable to provide different fluid flowbypass paths when activated, or both.

Adjustable passive choke devices as described herein may be useful inoilfield operations such as, but not limited to, enhanced oil recovery(EOR)-type operations, water injection into wells, or the like. By wayof example, adjustable passive choke devices as described herein may beused for controlling fluid flow rate through an injection well in an oilrecovery operation. It will be appreciated that, typically, fluid issupplied to such injection wells through a common line in communicationwith a fluid pump. It will be understood, however, that adjustablepassive choke devices as described herein may be of use in a widevariety of suitable applications where adjustable control of flow rateis needed or desired, and are not limited to oilfield-type operations.

In another embodiment, there is provided herein a fluid transport systemcomprising:

-   -   one, two or more fluid distribution lines;    -   a common line for supplying a fluid to the one, two or more        fluid distribution lines;    -   a pump for supplying the fluid to the common line; and    -   at least one adjustable passive choke device as described        hereinabove positioned before or within at least one of the        fluid distribution lines for controlling flow rate therethrough        and/or pressure downstream thereof.

In certain further embodiments, operation of the one or more adjustablepassive choke devices may be controlled by a programmable logiccontroller (PLC) or other computer-based controller as describedhereinabove.

In still further embodiments, the one or more adjustable passive chokedevices may control flow rate such that fluid flow rate through two ormore fluid distribution lines is substantially equal, or such that fluidflow rate between the two or more fluid distribution lines is maintainedat a predetermined ratio, above a predetermined lower ratio limit, belowa predetermined upper ratio limit, or within a predetermined ratiorange.

In even further embodiments, the one or more adjustable passive chokedevices may adapt to changes in fluid flow resistance in the fluiddistribution lines such that flow rate and/or pressure through the fluiddistribution lines remains substantially constant, or withinpredetermined range(s).

As will be understood, in certain embodiments, the fluid distributionlines may be injection wells in an oil recovery operation, and thecommon line may be a supply line providing, for example, a polymer orother EOR fluid for downhole injection, or water for downhole injection,or the like. It will be understood, however, that such fluid transportsystems as described herein may be of use in a wide variety of suitableapplications where adjustable control of flow rate is needed or desired,and are not limited to oilfield-type operations.

In still another embodiment, there is provided herein a method forcontrolling a flow rate and/or pressure of a fluid through a fluiddistribution line, said method comprising:

-   -   reducing the fluid flow rate by passing the fluid through a flow        resistance element; and    -   increasing the fluid flow rate by passing the fluid through a        fluid flow bypass path which bypasses all, or a portion, of the        flow resistance element;

as needed so as to maintain the flow rate, the pressure, or both, of thefluid through the fluid distribution line at predetermined value(s),above predetermined lower limit(s), below predetermined upper limit(s),or within predetermined range(s).

In certain embodiments, such methods may be performed by operating anadjustable passive choke device as described hereinabove. In certainfurther embodiments, the method may be an automated method performed bya programmable logic controller (PLC) or other computer-based controlleras described hereinabove.

EXAMPLE 1 Automated Adjustable Passive Choke Device and System

An example of an adjustable passive choke device for controlling fluidflow rate, downstream pressure, or both, is described in further detailbelow with reference to FIG. 1. This figure depicts an example of anadjustable passive choke device (1) which is installed at an injectionwell (15) in an oil recovery operation.

The adjustable passive choke device (1) of FIG. 1 is for controllingfluid flow rate and/or pressure through the injection well (15). Thedevice (1) includes a fluid conduit (2) in the form of a pipe having afirst end (3), a second end (4), and an intervening portion (5)therebetween. The intervening portion (5) comprises a flow resistanceelement (6) for reducing a flow rate of a fluid when the fluid is passedthrough the fluid conduit (2) from the first end (3) to the second end(4). The flow resistance element (6) in this example is a coilchoke-type resistance element comprising a plurality of loops or coils(11) for reducing fluid flow rate by frictional line loss.

The adjustable passive choke device of FIG. 1 further includes aplurality of selectable bypass lines (7) connected upstream (at upstreamconnections (9)) and downstream (at downstream connections (10)) ofvarious portions of the flow resistance element (6). In the illustratedexample, the flow resistance element (6) includes a 1-loop section, a2-loop section, a 4-loop section, and an 8-loop section connected inseries, each having a selectable bypass line (7) associated therewith.Each selectable bypass line (7) is operable to provide a fluid flowbypass path (8) bypassing a corresponding section of the flow resistanceelement (6) when activated. As such, the illustrated adjustable passivechoke device (1) may be configured to flow fluid through 0, 1, 2, 3, 4,5, 6, 7, 8, 9, 10,11, 12, 13, 14, or 15 loops (11), depending on theflow resistance desired, by selecting the appropriate combination ofactivated/deactivated selectable bypass lines (7). Even furtheradjustment over flow resistance may be possible by partially activatingone or more of the selectable bypass lines (7) to allow a portion, butnot all, of the fluid to bypass the associated resistance elementloop(s). In the device (1) illustrated in FIG. 1, fluid flow through theselectable bypass lines is controlled by one or more valves (12). Inthis example, the valves (12) are automated solenoid valves.

The device illustrated in FIG. 1 further comprises a flow meter (13)downstream of the flow resistance element (6) for determining fluid flowrate. The illustrated device may also optionally include one or morepressure gauges (not shown) and/or other sensors for determiningpressure drop across the coils (i.e. (Δ pressure)/(length)) and/or fordetermining downstream pressure. Such pressure drop across the coilsand/or downstream pressure may optionally be determined and/or monitoredon an ongoing basis, and may each be used as parameter(s) whendetermining activation/deactivation of the selectable bypass line(s) ofthe adjustable passive choke device so as to maintain a desired flowrate and/or pressure in the system. The person of skill in the arthaving regard to the teachings herein will be able to select the numberand location of such optional pressure gauges and/or other sensors so asto provide pressure information suitable for a particular application.

In FIG. 1, fluid flow through the selectable bypass lines (7) iscontrolled by a programmable logic controller (PLC) (14). Activation anddeactivation of the selectable bypass lines (7), and selection of activefluid flow bypass paths (8) is automated, such that flow rate,downstream pressure, or both, is maintained at predetermined value(s),above predetermined lower limit(s), below predetermined upper limit(s),or within predetermined range(s).

The device (1) illustrated in FIG. 1, which is installed at an injectionwell (15) in an oil recovery operation, and which is supplied with fluidby a common supply line (16), also provides an example of a fluidtransport system as described herein.

Such a system may comprise two or more fluid distribution lines (i.e.injection wells (15)), a common line (16) for supplying a fluid to thetwo or more fluid distribution lines (15); and at least one adjustablepassive choke device (1) positioned before or within at least one of thefluid distribution lines (15) for controlling flow rate therethrough.While FIG. 1 depicts a single injection well (15), a second injectionwell supplied by common line (16) may be located downstream of theportion of the system shown in FIG. 1, for example.

In the illustrated system, a pump (not shown) is used for supplying thefluid to the common line (16). Although a pump is being used in theillustrated system for supplying the fluid to the common line (16), andflowing the fluid through the common line (16) to the injection wells(15), it will be understood that other suitable apparatus may also beused for supplying and/or flowing the fluid through the system.

In the illustrated embodiment in FIG. 1, operation of the adjustablepassive choke device (1) is controlled by a programmable logiccontroller (PLC) (14) such that adjustable passive choke device (1)controls flow rate such that fluid flow rate through the two fluiddistribution lines (i.e. injection wells (15)) is substantially equal,or such that fluid flow rate between the two or more fluid distributionlines (15) is maintained at a predetermined ratio, above a predeterminedlower ratio limit, below a predetermined upper ratio limit, or within apredetermined ratio range. In the illustrated embodiment, the automatedadjustable passive choke device (1) adapts to changes in fluid flowresistance in the fluid distribution lines (15) such that flow rateand/or pressure through the fluid distribution lines (15) remainssubstantially constant, or within predetermined range(s).

One or more illustrative embodiments have been described by way ofexample. It will be understood to persons skilled in the art that anumber of variations and modifications can be made without departingfrom the scope of the invention as defined in the claims.

1. An adjustable passive choke device for controlling fluid flow rate or pressure, said device comprising: a fluid conduit having a first end, a second end, and an intervening portion therebetween, the intervening portion comprising a flow resistance element configured for reducing a flow rate of a fluid when the fluid is passed through the fluid conduit from the first end to the second end; and a selectable bypass line connected upstream and downstream of at least a portion of the flow resistance element, the selectable bypass line being configured to provide a fluid flow bypass path bypassing at least a portion of the flow resistance element when activated; whereby activation of the selectable bypass line configures the adjustable passive choke device for increased flow rate by at least partially opening the fluid flow bypass path, and deactivation of the selectable bypass line configures the adjustable passive choke device for decreased flow rate by at least partially closing the fluid flow bypass path.
 2. The device of claim 1, wherein the selectable bypass line comprises two or more upstream connections, downstream connections, or both, and is configured to provide a plurality of selectable fluid flow bypass paths, with each path bypassing a different proportion of the flow resistance element.
 3. The device of claim 1, wherein the flow resistance element comprises one or more loops or coils for reducing fluid flow rate by frictional line loss.
 4. The device of claim 1, further comprising one or more valves for controlling fluid flow through the selectable bypass line.
 5. The device of claim 1, further comprising at least one of a flow meter downstream of the flow resistance element for determining fluid flow rate and a pressure gauge or pressure sensor for determining pressure downstream of the flow resistance element.
 6. The device of claim 1, further comprising one or more pressure gauges or pressure sensors for determining a pressure drop across the at least one portion of the flow resistance element.
 7. The device of claim 1, further comprising a programmable logic controller (PLC) for controlling fluid flow through the selectable bypass line.
 8. The device of claim 2, wherein the activation and the deactivation of the selectable bypass line and selection of at least one fluid flow bypass path from the plurality of selectable fluid flow bypass paths, is automated, and wherein the fluid flow rate or downstream pressure is maintained at a predetermined value, above a predetermined lower limit, below a predetermined upper limit, or within a predetermined range.
 9. The device of claim 8, wherein the activation and the deactivation of the selectable bypass line and the selection of the at least one fluid flow bypass path, is determined at least in part by at least one of a measured flow rate parameter, a measured pressure drop parameter, or a measured downstream pressure parameter.
 10. The device of claim 1, further comprising two or more flow resistance elements.
 11. The device of claim 10, wherein the two or more flow resistance elements are configured to provide the same or different resistance to fluid flow therethrough.
 12. The device of claim 10, wherein the selectable bypass line is configured to provide one or more fluid flow bypass paths bypassing at least a portion of the two or more flow resistance elements.
 13. The device of claim 1, further comprising two or more individually selectable bypass lines, with each configured to provide different fluid flow bypass paths when activated.
 14. (canceled)
 15. The device of claim 1, wherein the flow resistance element comprises a 2× multiplier configuration for providing incremental doubling of length or flow resistance between portions of the flow resistance element.
 16. A fluid transport system comprising: at least one fluid distribution lines; a common line for supplying a fluid to the at least one fluid distribution lines; a pump for supplying the fluid to the common line, and at least one adjustable passive choke device according to claim 1 positioned before or within the at least one fluid distribution lines for controlling fluid flow rate therethrough or pressure downstream thereof.
 17. The system of claim 16, further comprising a programmable logic controller (PLC) for controlling the at least one adjustable passive choke device.
 18. The system of claim 16, further comprising at least two fluid distribution lines, wherein the at least one adjustable passive choke devices is configured to control fluid flow rate whereby the such that fluid flow rate through the at least two fluid distribution lines is substantially equal, or whereby the ratio of fluid flow rate between the at least two fluid distribution lines is: maintained at a predetermined ratio, above a predetermined lower ratio limit, below a predetermined upper ratio limit, or within a predetermined ratio range.
 19. The system of claim 18, wherein the at least one adjustable passive choke devices is configured to adapt to changes in fluid flow resistance in the at least two fluid distribution lines, whereby the fluid flow rate or pressure through the at least two fluid distribution lines remains substantially constant or within a predetermined range.
 20. The system of claim 16, wherein the fluid distribution lines are injection wells in an oil recovery operation or in a water injection operation.
 21. A method for controlling fluid flow rate or pressure through at least one fluid distribution line, comprising: providing an adjustable passive choke device having a fluid flow bypass path; passing a fluid through the adjustable passive choke device; controlling the fluid flow rate by performing at least one of: increasing the fluid flow rate by at least partially opening the fluid flow bypass path; and decreasing the fluid flow rate by at least partially closing the fluid flow bypass path, wherein the at least one fluid distribution line is configured as at least one injection well in an oil recovery operation or in a water injection operation. 